JP7352884B2 - Infrared sensors and phononic crystals - Google Patents

Description

The present disclosure relates to an infrared sensor with a beam having a phononic crystal structure. Further, the present disclosure relates to a phononic crystal body having a phononic crystal structure.

In the field of infrared sensors, a structure has been proposed in which an infrared receiver is separated from a base substrate using a beam. This structure is intended to thermally insulate the infrared light receiving section from the base substrate. In an infrared sensor having this structure, the higher the heat insulation performance of the beam, the higher the infrared light reception sensitivity.

Patent Document 1, Patent Document 2, and Non-Patent Document 1 disclose periodic structures composed of a plurality of through holes that reduce the thermal conductivity of a thin film. In this periodic structure, when the thin film is viewed from above, through-holes are regularly arranged at a period on the order of nanometers (range from 1 nm to 1000 nm). This periodic structure is a type of phononic crystal structure. This type of phononic crystal structure is a periodic structure in which the minimum unit constituting the arrangement of through holes is a unit cell. The thermal conductivity of a thin film can be reduced, for example, by making it porous. This is because the voids introduced into the thin film by making it porous reduce the thermal conductivity of the thin film. However, according to the phononic crystal structure, the thermal conductivity of the base material itself constituting the thin film can be reduced. Therefore, it is expected that the thermal conductivity will be further reduced compared to simply making it porous.

Patent Document 3 discloses an infrared sensor using a beam having a phononic crystal structure.

US Patent Application Publication No. 2017/0047499 US Patent Application Publication No. 2017/0069818 JP2017-223644A

Nomura et al., "Impeded thermal transport is Si multiscale hierarchical architectures with phononic crystal nanostructures", Physical ReviewB 91, 205422 (2015)

There is a need for technology that further increases the sensitivity of infrared sensors.

The present disclosure provides techniques to further increase the sensitivity of infrared sensors.

The present disclosure provides the following infrared sensor.

An infrared sensor, comprising:
Base board;
Infrared receiver; and beam;
here,
The beam has a connection portion connected to the base substrate and/or a member on the base substrate, and a separation portion spaced apart from the base substrate,
The infrared light receiving part and the beam are joined to each other at the separation part,
The infrared light receiving section is supported by the beam having the spacing section while being spaced apart from the base substrate,
A section of the beam located between the joint part with the infrared light receiving part and the connection part has a phononic crystal structure constituted by a plurality of regularly arranged through holes,
The phononic crystal structure includes a first domain and a second domain that are phononic crystal regions,
The first domain is composed of the plurality of through holes regularly arranged in a first direction in a plan view,
The second domain is composed of the plurality of through holes regularly arranged in a second direction different from the first direction in a plan view, and
The infrared receiver is a thermopile infrared receiver or a bolometer infrared receiver:
When the infrared receiving section is a thermopile infrared receiving section,
The beam includes a first region having a first Seebeck coefficient, a second region having a second Seebeck coefficient different from the first Seebeck coefficient, and the first region and the second region. a bonding region in which the bonding regions are bonded to each other, and
the infrared light receiving portion and the bonding region of the beam are bonded to each other;
When the infrared receiver is a bolometer infrared receiver,
The infrared sensor further includes:
a first wiring and a second wiring electrically connected to the infrared receiving section;
a first signal processing circuit electrically connected to the first wiring; and a second signal processing circuit electrically connected to the second wiring.

The insulating performance of the beam in the infrared sensor of the present disclosure is high. Therefore, the infrared sensor of the present disclosure can have high sensitivity to infrared rays.

FIG. 1A is a plan view schematically showing the infrared sensor of Embodiment 1. FIG. 1B is a cross-sectional view showing the cross section 1B-1B of the infrared sensor of FIG. 1A. FIG. 2 is a plan view schematically showing an example of a phononic crystal structure that a beam of an infrared sensor according to the present disclosure has. FIG. 3A is a schematic diagram showing the unit cell and its orientation in the first domain included in the phononic crystal structure of FIG. 2. FIG. FIG. 3B is a schematic diagram showing the unit cell and its orientation in the second domain included in the phononic crystal structure of FIG. FIG. 4 is an enlarged view of region R1 of the phononic crystal structure in FIG. FIG. 5 is a plan view schematically showing another example of the phononic crystal structure that the beam of the infrared sensor of the present disclosure has. FIG. 6 is an enlarged view of region R2 of the phononic crystal structure in FIG. FIG. 7 is a plan view schematically showing another example of the phononic crystal structure of the beam of the infrared sensor of the present disclosure. FIG. 8 is an enlarged view of region R3 of the phononic crystal structure in FIG. FIG. 9 is a plan view schematically showing yet another example of the phononic crystal structure that the beam of the infrared sensor of the present disclosure has. FIG. 10 is a plan view schematically showing another example of the phononic crystal structure that the beam of the infrared sensor of the present disclosure has. FIG. 11 is a plan view schematically showing another example of the phononic crystal structure that the beam of the infrared sensor of the present disclosure has. FIG. 12A is a schematic diagram showing an example of a unit cell of a phononic crystal structure that a beam of an infrared sensor of the present disclosure has. FIG. 12B is a schematic diagram showing another example of a unit cell of a phononic crystal structure that a beam of an infrared sensor of the present disclosure has. FIG. 13 is a plan view schematically showing another example of the phononic crystal structure that the beam of the infrared sensor of the present disclosure has. FIG. 14 is a plan view schematically showing another example of the phononic crystal structure that the beam of the infrared sensor of the present disclosure has. FIG. 15A is a schematic diagram showing an example of a unit cell of a phononic crystal structure that a beam of an infrared sensor of the present disclosure has. FIG. 15B is a schematic diagram showing another example of the unit cell of the phononic crystal structure that the beam of the infrared sensor of the present disclosure has. FIG. 15C is a schematic diagram showing another example of a unit cell of a phononic crystal structure that a beam of an infrared sensor of the present disclosure has. FIG. 15D is a schematic diagram showing another example of the unit cell of the phononic crystal structure that the beam of the infrared sensor of the present disclosure has. FIG. 16A is a schematic cross-sectional view for explaining an example of a method for manufacturing the infrared sensor of Embodiment 1. FIG. 16B is a schematic cross-sectional view for explaining an example of a method for manufacturing the infrared sensor of Embodiment 1. FIG. 16C is a schematic cross-sectional view for explaining an example of a method for manufacturing the infrared sensor of Embodiment 1. FIG. 16D is a schematic cross-sectional view for explaining an example of a method for manufacturing the infrared sensor of Embodiment 1. FIG. 16E is a schematic cross-sectional view for explaining an example of a method for manufacturing the infrared sensor of Embodiment 1. FIG. 17A is a plan view schematically showing an infrared sensor according to the second embodiment. FIG. 17B is a cross-sectional view taken along section 17B-17B of the infrared sensor of FIG. 17A. FIG. 18A is a plan view schematically showing an infrared sensor of Embodiment 3. FIG. 18B is a cross-sectional view taken along section 18B-18B of the infrared sensor of FIG. 18A. FIG. 19A is a schematic cross-sectional view for explaining an example of a method for manufacturing the infrared sensor of Embodiment 3. FIG. 19B is a schematic cross-sectional view for explaining an example of a method for manufacturing the infrared sensor of Embodiment 3. FIG. 19C is a schematic cross-sectional view for explaining an example of a method for manufacturing the infrared sensor of Embodiment 3. FIG. 19D is a schematic cross-sectional view for explaining an example of a method for manufacturing the infrared sensor of Embodiment 3. FIG. 20 is a plan view schematically showing the infrared sensor of Embodiment 4. FIG. 21A is a plan view schematically showing an infrared sensor of Embodiment 5. FIG. 21B is a cross-sectional view taken along section 21B-21B of the infrared sensor of FIG. 21A. FIG. 22A is a plan view schematically showing the infrared sensor of Embodiment 6. FIG. 22B is a cross-sectional view taken along section 22B-22B of the infrared sensor of FIG. 22A. FIG. 23A is a plan view schematically showing the infrared sensor of Embodiment 7. FIG. 23B is a cross-sectional view taken along section 23B-23B of the infrared sensor of FIG. 23A.

(Findings that formed the basis of this disclosure)
In insulators and semiconductors, heat is primarily transported by lattice vibrations called phonons. The thermal conductivity of a material made of an insulator or a semiconductor is determined by the phonon dispersion relationship of the material. The phonon dispersion relationship means the relationship between frequency and wave number or band structure. In insulators and semiconductors, heat-carrying phonons span a wide frequency band from 100 GHz to 10 THz. This frequency band is a thermal band. The thermal conductivity of a material is determined by the dispersion relationship of phonons in the thermal band.

According to the above-described phononic crystal structure, the dispersion relationship of phonons in the material can be controlled by the periodic structure of the through holes. That is, according to the phononic crystal structure, the thermal conductivity of the material itself, such as the base material of the thin film, can be controlled. In particular, the formation of a phononic band gap (PBG) by a phononic crystal structure can significantly reduce the thermal conductivity of a material. Phonons cannot exist within the PBG. Therefore, the PBG located in the thermal zone can become a gap in thermal conduction. Furthermore, even in frequency bands other than PBG, the slope of the phonon dispersion curve is reduced by PBG. Reducing the tilt reduces the group velocity of phonons, which reduces the rate of heat transfer. These points greatly contribute to reducing the thermal conductivity of the material.

According to studies by the present inventors, the degree of reduction in thermal conductivity brought about by the phononic crystal structure depends on the angle formed between the direction of heat transfer and the orientation of the unit cell of the phononic crystal structure. This is considered to be because elements related to heat conduction, such as the bandwidth of the PBG, the number of PBGs, and the average group velocity of phonons, depend on the angle. Regarding heat transfer, from a macroscopic perspective, phonons flow from a high temperature to a low temperature direction. On the other hand, if we focus on the micro region on the order of nanometers, there is no directivity in the direction in which phonons flow. That is, microscopically, the direction in which phonons flow is not uniform.

Each of the above-mentioned patent documents and non-patent documents discloses a member having a plurality of phononic crystal regions in which the orientation of the unit cell is uniformly aligned. However, in these members, from a microscopic perspective, the interaction is maximum for phonons flowing in a certain specific direction, but the interaction is weaker for phonons flowing in other directions. On the other hand, the beam included in the infrared sensor of the present disclosure has two or more phononic crystal regions in which the orientations of the unit cell are different from each other. Therefore, from a micro perspective, it is possible to enhance the interaction with each phonon flowing in multiple directions. This feature brings about a further reduction in the thermal conductivity of the beam as a macroscopic member, that is, a further improvement in the heat insulation performance.

(Embodiments of the present disclosure)
Embodiments of the present disclosure will be described below with reference to the drawings. Note that the embodiments described below are all inclusive or show specific examples. Numerical values, shapes, materials, components, arrangement positions of components, connection forms, process conditions, steps, order of steps, etc. shown in the following embodiments are examples, and do not limit the present disclosure. Furthermore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the most significant concept will be described as arbitrary constituent elements. Note that each figure is a schematic diagram and is not necessarily strictly illustrated.

(Embodiment 1)
An infrared sensor of Embodiment 1 is shown in FIGS. 1A and 1B. FIG. 1B shows a cross section 1B-1B of the infrared sensor 1A of FIG. 1A. The infrared sensor 1A in FIGS. 1A and 1B is a thermopile infrared sensor. The infrared sensor 1A includes a base substrate 11, a thermopile infrared receiver 12A, and a beam 13. The infrared sensor 1A also includes a first signal processing circuit 14A, a second signal processing circuit 14B, a first wiring 15A, and a second wiring 15B. The signal processing circuits 14A, 14B and the wirings 15A, 15B are provided on the base substrate 11.

The beam 13 has connecting portions 131A and 131B connected to the base substrate 11, and a separation portion 132 spaced apart from the base substrate 11. The beam 13 has connecting portions 131A and 131B at both ends. The infrared light receiving section 12A and the beam 13 are joined to each other at the separation section 132. The infrared light receiving section 12A is joined to the upper surface of the beam 13. The position where the infrared light receiving section 12A and the beam 13 are joined is between both ends of the beam 13, more specifically, near the center of the beam 13. The infrared light receiving section 12A is supported by a beam 13 having a spacing section 132 while being spaced apart from the base substrate 11. The beam 13 is a double-end beam.

The base substrate 11 has a recess 17 on the upper surface 16 where the infrared light receiving section 12A is provided. In plan view, the area of the recess 17 is larger than the area of the infrared light receiving section 12A. Furthermore, in a plan view, the infrared light receiving section 12A is surrounded by the outer edge of the recess 17. The recess 17 is located between the infrared light receiving section 12A and the beam 13, and the base substrate 11. In a cross-sectional view, the infrared light receiving section 12A and the beam 13 are suspended above the recess 17 of the base substrate 11. Note that both ends of the beam 13 are connected to the side walls of the recess 17. Note that in this specification, "planar view" means viewing the object from a direction perpendicular to the main surface of the object. Moreover, the "principal surface" means the surface having the largest area.

The beam 13 is a single layer. The beam 13 has a first region 301 having a first Seebeck coefficient, a second region 302 having a second Seebeck coefficient different from the first Seebeck coefficient, and a first region 301 and a second region. 302 has a bonding region 303 that is bonded to each other. The first region 301 and the second region 302 are joined to each other at one end 304, 305 of each. The first region 301 and the second region 302 joined in the joining region 303 constitute a thermocouple element. The joining region 303 is located at a position overlapping the infrared sensor 1A in plan view. The joining region 303 is located, for example, at the center of the infrared sensor 1A in plan view. The infrared light receiving section 12A and the joining region 303 in the beam 13 are joined to each other. The difference between the first Seebeck coefficient and the second Seebeck coefficient is, for example, 10 μV/K or more. Note that the Seebeck coefficient in this specification means a value at 25°C.

The first wiring 15A is electrically connected to the first region 301 at the other end 306 of the first region 301. The end portion 306 is located at the connecting portion 131A of the beam 13. The second wiring 15B is electrically connected to the second region 302 at the other end 307 of the second region 302. The end portion 307 is located at the connecting portion 131B of the beam 13. The first wiring 15A electrically connects the first region 301 in the beam 13 and the first signal processing circuit 14A. The second wiring 15B electrically connects the second region 302 in the beam 13 and the second signal processing circuit 14B. In FIGS. 1A and 1B, the first signal processing circuit 14A and the second signal processing circuit 14B are two mutually independent members. However, the first signal processing circuit 14A and the second signal processing circuit 14B may be a single member in which both circuits are integrated.

A section 134 (134A, 134B) located in the beam 13 between the joint 133 with the infrared light receiving section 12A and the connection parts 131A, 131B with the base substrate 11, the first wiring 15A, and the second wiring 15B. has a phononic crystal structure A. When the beam 13 has a plurality of sections 134, all the sections have the phononic crystal structure A, for example.

When infrared rays are incident on the infrared light receiving section 12A, the temperature of the infrared light receiving section 12A increases. At this time, the temperature of the infrared light receiving section 12A increases more as it is thermally insulated from the base substrate 11, which is a heat bath, and the members on the base substrate 11. In the thermocouple element joined to the thermopile infrared light receiving section 12A, as the temperature rises, an electromotive force is generated due to the Seebeck effect. The generated electromotive force is processed by signal processing circuits 14A and 14B, and infrared rays are detected. Depending on the signal processing, the infrared sensor 1A can measure the intensity of infrared rays and/or measure the temperature of the object.

The first region 301 is comprised of a first material having a first Seebeck coefficient. The second region 302 is comprised of a second material having a second Seebeck coefficient different from the first Seebeck coefficient. The first material and the second material may be semiconductors or insulators instead of metals. This is because the medium that transports heat in metals is mainly free electrons, not phonons. Semiconductors include, for example, single-element semiconductors such as Si or Ge, compound semiconductors such as SiN, SiC, SiGe, GaAs, InAs, InSb, InP, GaN, or AlN, as well as Fe ₂ O ₃ , VO ₂ , TiO ₂ , or It is an oxide semiconductor such as SrTiO ₃ . However, the semiconductor that is the first material or the second material is not limited to these examples. The first material and the second material typically have different compositions. However, the first material and the second material, which are semiconductors, can have the same basic composition when their conductivity types are different. The conductivity type of a semiconductor can be controlled by known techniques such as doping. For example, the first material may be a p-type semiconductor and the second material may be an n-type semiconductor. In this case, the first region 301 is a p-type region and the second region 302 is an n-type region. In a specific example, a single layer beam 13 made of single crystal Si has a first region 301 and a second region 302 that are doped. Processing technology for single crystal Si has been established. Therefore, this example has excellent manufacturability.

The first material and the second material may be single crystal materials in which the order of atomic arrangement extends over long distances, polycrystalline materials, or amorphous materials.

Base substrate 11 is typically made of a semiconductor. The semiconductor is, for example, Si. An oxide film may be formed on the upper surface 16 of the base substrate 11 made of Si. The oxide film is, for example, a SiO ₂ film. However, the configuration of the base substrate 11 is not limited to the above example.

The infrared light receiving section 12A is made of, for example, a silicon-based semiconductor. The silicon-based semiconductor is, for example, Si or SiGe. However, the configuration of the infrared light receiving section 12A is not limited to the above example.

The wirings 15A and 15B are made of, for example, doped semiconductor or metal. The metal is, for example, a species with low thermal conductivity, such as Ti or TiN. However, the configuration of the wirings 15A and 15B is not limited to the above example.

The signal processing circuits 14A and 14B may have a known configuration.

The following description relates to the phononic crystal structure A that the beam 13 has. The beam 13 may have the phononic crystal structure A in portions other than the sections 134A and 134B.

An example of the phononic crystal structure A is shown in FIG. FIG. 2 shows a plan view of a part of the beam 13. The beam 13 is, for example, a thin film having a thickness of 10 nm or more and 500 nm or less. The beam 13 is rectangular in plan view. The long side of the beam 13 coincides with the direction connecting the infrared light receiving section 12A and the first wiring 15A or the second wiring 15B, that is, the direction of macroscopic heat transfer in the infrared sensor 1A. The beam 13 is provided with a plurality of through holes 20 extending in the thickness direction of the beam 13. The phononic crystal structure A that the beam 13 has is a two-dimensional phononic crystal structure in which a plurality of through holes 20 are regularly arranged in the in-plane direction.

The phononic crystal structure A has a first domain 21A, which is a phononic crystal region, and a second domain 21B, which is a phononic crystal region. The first domain 21A has a phononic single crystal structure composed of a plurality of through holes 20 regularly arranged in the first direction in a plan view. The second domain 21B has a phononic single crystal structure composed of a plurality of through holes 20 regularly arranged in a second direction different from the first direction in a plan view. In each single crystal structure, the diameter and arrangement period of the plurality of through holes 20 are the same. Moreover, in each single crystal structure, the orientation of unit cell 91A or 91B constituted by a plurality of regularly arranged through holes 20 is the same. The shapes of the first domain 21A and the second domain 21B are rectangular in plan view. The shape of the first domain 21A and the shape of the second domain 21B are the same in plan view. The phononic crystal structure A is also a phononic polycrystalline structure 22 that is a composite of a plurality of phononic single crystal structures.

The domain, which is a phononic crystal region, is a region having an area of, for example, 25P ² or more in plan view, where P is the period of arrangement of the through holes 20. In order to control the phonon dispersion relationship by the phononic crystal structure, the domain may have an area of at least 25P ² or more. In a square domain in plan view, by setting the period to 5×P or more, it is possible to secure an area of 25P ² or more.

As shown in FIGS. 3A and 3B, in the phononic crystal structure A, the orientation 23A of the unit cell 91A in the first domain 21A and the orientation 23B of the unit cell 91B in the second domain 21B are different from each other in plan view. There is. The angle formed by the orientation 23A and the orientation 23B is, for example, 10 degrees or more in plan view. However, when the unit cell 91A and the unit cell 91B are the same and have n-fold rotational symmetry, the upper limit of the angle formed by the orientation 23A and the orientation 23B is less than 360/n degrees. Note that when the unit cell has n-fold rotational symmetry with respect to a plurality of n's, the maximum n is used as n that determines the upper limit of the above angle. For example, a hexagonal lattice has two-fold rotational symmetry, three-fold rotational symmetry, and six-fold rotational symmetry. At this time, "6" is used for n which determines the upper limit of the angle. That is, regarding the unit lattices 91A and 91B, which are hexagonal lattices, the angle formed by the orientation 23A and the orientation 23B is less than 60 degrees. The phononic crystal structure A has at least two or more phononic crystal regions whose unit cell orientations are different from each other. As long as this condition is satisfied, the phononic crystal structure A may further include any phononic crystal region and/or a region having no phononic crystal structure.

Here, as for the embodiment of the phononic crystal structure A, it is desirable that the number of regions not having a phononic crystal structure is as small as possible. The reason for this is that as the number of regions having a phononic crystal structure increases, the heat insulation performance of the phononic crystal structure A increases, that is, the sensitivity of the infrared sensor increases. Another reason is that the temperature difference between the infrared receiving section 12A and the base substrate 11 becomes large. Infrared rays are received not only by the infrared light receiving section 12A but also by the beam 13. When the number of regions that do not have a phononic crystal structure in the phononic crystal structure A is large, the infrared ray receiving area of the beam 13 is large. Therefore, in this case, the beam 13 receives a large amount of infrared rays. This reduces the temperature difference between the infrared light receiving section 12A and the base substrate 11. On the other hand, when the number of regions having a phononic crystal structure in the phononic crystal structure A is large, the amount of infrared rays received by the beam 13 is small. Therefore, it is possible to maintain a larger temperature difference between the infrared light receiving section 12 and the base substrate 12. As a result, the sensitivity of the infrared sensor increases.

The orientation of the unit cell can be determined based on any rule. However, it is necessary to apply the same rules to determine the orientation of the unit cell between different domains. The orientation of the unit cell is, for example, the direction in which the average group velocity of phonons is the slowest when the macroscopic heat transfer direction in the phononic crystal structure A is determined as one direction. Alternatively, the orientation of the unit cell is, for example, the direction in which a straight line bisects the angle formed by the two non-parallel sides that constitute the unit cell. However, it is necessary to define the two sides using the same rules between different domains. Alternatively, the orientation of the unit cell is, for example, a straight line direction connecting two nearest holes.

An enlarged view of region R1 of the phononic crystal structure A of FIG. 2 is shown in FIG. 4. At the interface 25 between the adjacent first domain 21A and second domain 21B, the orientations 23A and 23B of the unit cells 91A and 91B change. The interface 25 in which the orientation of the unit cell changes provides a large interfacial resistance to heat flowing macroscopically through the phononic crystal structure A. This interfacial resistance is based on the mismatch in phonon group velocity that occurs between the first domain 21A and the second domain 21B. This interfacial resistance contributes to reducing the thermal conductivity in the beam 13 having the phononic crystal structure A. Note that in FIG. 4, the interface 25 extends linearly in plan view. Further, the interface 25 extends in the width direction of the rectangular beam 13 in plan view. The width direction may be a direction perpendicular to the extending direction of the center line of the beam 13 determined by the macroscopic heat transfer direction. The interface 25 divides the phononic crystal structure A perpendicularly to the macroscopic heat transfer direction in plan view.

In the phononic crystal structure A of FIG. 2, the period P of the arrangement of the plurality of through holes 20 in the first domain 21A is equal to the period P of the arrangement of the plurality of through holes 20 in the second domain 21B.

In the phononic crystal structure A of FIG. 2, the diameter of the plurality of regularly arranged through holes 20 in the first domain 21A is equal to the diameter of the plurality of regularly arranged through holes 20 in the second domain 21B.

In the phononic crystal structure A of FIG. 2, the type of unit cell 91A in the first domain 21A and the type of unit cell 91B in the second domain 21B are the same. Both the unit lattice 91A and the unit lattice 91B in FIG. 2 are hexagonal lattices.

The shape of each domain in plan view is not limited. The shape of each domain in plan view is, for example, a polygon including a triangle, a square, and a rectangle, a circle, an ellipse, and a composite shape thereof. The shape of each domain in plan view may be amorphous. Further, the number of domains that the phononic crystal structure A has is not limited. The greater the number of domains that the phononic crystal structure A has, the greater the effect of interfacial resistance due to the interface between the domains. Furthermore, the size of each domain that the phononic crystal structure A has is not limited.

When the plurality of sections 134 in the beam 13 have a phononic crystal structure A, the specific configuration of each phononic structure A may be the same or different from each other.

An example of the phononic crystal structure A will be shown below.

In the polycrystalline structure 22 which is the phononic crystal structure A in FIGS. 5 and 6, the interface 25 between the adjacent first domain 21A and second domain 21B extends in the direction of the long side of the rectangular beam 13 in plan view. There is. The direction of the long side may be the direction of macroscopic heat transfer. Other than this point, the phononic crystal structure A of FIGS. 5 and 6 has the same configuration as the phononic crystal structure A of FIG. 2. The interface 25 divides the phononic crystal structure A in parallel to the macroscopic heat transfer direction in plan view. Note that FIG. 6 is an enlarged view of region R2 in FIG.

In the phononic crystal structure A of FIGS. 2 and 5, the size of the first domain 21A and the size of the second domain 21B are the same in plan view. However, in plan view, the sizes of the first domain 21A and the second domain 21B of the phononic structure A may be different from each other.

In the polycrystalline structure 22 which is the phononic crystal structure A in FIGS. 7 and 8, the second domain 21B is surrounded by the first domain 21A in plan view. The shapes of the first domain 21A and the second domain 21B are rectangular in plan view. However, the size of the first domain 21A and the size of the second domain 21B are different in plan view. The interface 25 between the second domain 21B and the first domain 21A surrounding the second domain 21B constitutes the outer edge of the second domain 21B in plan view. Other than these points, the phononic crystal structure A of FIGS. 7 and 8 has the same configuration as the phononic crystal structure A of FIG. 2. Note that FIG. 8 is an enlarged view of region R3 in FIG. 7.

Furthermore, in the phononic crystal structure A shown in FIGS. 7 and 8, the interface 25 has a bent portion.

Furthermore, the phononic crystal structure A in FIGS. 7 and 8 has a second domain 21B that is not in contact with the side of the beam 13.

In the polycrystalline structure 22 which is the phononic crystal structure A in FIG. 9, the first domain 21A and the second domain 21B are arranged apart from each other in plan view. More specifically, in a plan view, a region 201 having no through hole 20 is provided between the first domain 21A and the second domain 21B in the long side direction of the beam 13. Other than this point, the phononic crystal structure A in FIG. 9 has the same configuration as the phononic crystal structure A in FIG. 2.

In the polycrystalline structure 22 that is the phononic crystal structure A in FIG. 10, the first domain 21A and the second domain 21B are spaced apart from each other in plan view. More specifically, in plan view, a region 202 having randomly provided through holes 20 is provided between the first domain 21A and the second domain 21B in the long side direction of the beam 13. In the region 202, the through holes 20 are not regularly arranged in plan view. Alternatively, in the region 202, the area of the regularly arranged regions is, for example, less than 25P ² in plan view. Here, P is the period of arrangement of the through holes 20. Other than this point, the phononic crystal structure A in FIG. 10 has the same configuration as the phononic crystal structure A in FIG. 2.

The polycrystalline structure 22, which is the phononic crystal structure A in FIG. 11, includes a plurality of domains 21A to 21G having mutually different shapes in plan view. Within each domain, the period of arrangement of the plurality of through holes 20 and the orientation of the unit cell are the same. However, between the domains 21A to 21G, the orientations of the unit cells are different from each other. Further, in plan view, the sizes and shapes of the domains 21A to 21G are different from each other. In this form, there are more unit cell orientations when looking at the entire phononic crystal structure A than in the forms exemplified above. Therefore, the effect of lowering thermal conductivity becomes more pronounced based on the difference in the orientation of the unit cell between domains. Further, in this form, the interfaces 25 between domains extend in a plurality of random directions in plan view. Therefore, the effect of lowering thermal conductivity based on interfacial resistance becomes more significant.

Moreover, in the phononic crystal structure A of FIG. 11, the interface 25 between the adjacent first domain 21A and second domain 21B extends in a direction inclined from the width direction of the beam 13 in plan view. The interface 25 also has a bent portion in plan view.

The polycrystalline structure 22, which is the phononic crystal structure A, may include a first domain 21A and a second domain 21B in which the period P of the arrangement of the through holes 20 and/or the diameter D of the through holes 20 are different from each other. The diameter D of the through hole 20 in the first domain 21A shown in FIG. 12A is different from the diameter D of the through hole 20 in the second domain 21B shown in FIG. 12B. Note that the period P of the arrangement of the through holes 20 in the first domain 21A shown in FIG. 12A is the same as the period P of the arrangement of the through holes 20 in the second domain 21B shown in FIG. 12B.

The phononic crystal structure A shown in FIG. 13 has a first domain 21A in which a plurality of through holes 20 having a relatively small period P and a diameter D are regularly arranged, and a first domain 21A having a relatively large period P and a diameter D. It has a second domain 21B in which a plurality of through holes 20 are regularly arranged. In addition, the phononic crystal structure A shown in FIG. It has a region 93 made up of through holes 20. Region 92 and region 93 are adjacent to each other. Similarly to the example shown in FIG. 11, the regions 92 and 93 each include a plurality of domains that have mutually different shapes in plan view and have mutually different orientations of unit cells. Further, the region 92 and the region 93 divide the phononic crystal structure A perpendicularly to the macroscopic heat transfer direction. In this form, since the frequency band of the phononic band gap formed in the first domain 21A and the frequency band of the phononic band gap formed in the second domain 21B are different, the effect of reducing thermal conductivity is particularly remarkable. becomes.

The phononic crystal structure A shown in FIG. 14 has a first domain 21A in which a plurality of through holes 20 having a relatively small period P and a diameter D are regularly arranged, and a first domain 21A having a relatively large period P and a diameter D. It includes a second domain 21B in which a plurality of through holes 20 are regularly arranged. The phononic crystal structure A in FIG. 14 includes a plurality of domains that have mutually different shapes in plan view and have mutually different unit cell orientations. In this form, since the frequency band of the phononic band gap formed in the first domain 21A and the frequency band of the phononic band gap formed in the second domain 21B are different, the effect of reducing thermal conductivity is particularly remarkable. becomes.

The period P of the arrangement of the through holes 20 is, for example, 1 nm or more and 300 nm or less. This is because the wavelength of heat-carrying phonons mainly ranges from 1 nm to 300 nm. The period P is determined by the center-to-center distance between adjacent through holes 20 in plan view (see FIGS. 12A and 12B).

The diameter D of the through hole 20 is expressed by the ratio D/P to the period P, and for example, D/P≧0.5. When the ratio D/P<0.5, the porosity in the beam 13 may be excessively reduced and the thermal conductivity may not be sufficiently reduced. The upper limit of the ratio D/P is, for example, less than 0.9 because adjacent through holes 20 do not touch each other. The diameter D is the diameter of the opening of the through hole 20. When the shape of the opening of the through hole 20 is a circle in plan view, the diameter D is the diameter of the circle. The shape of the opening of the through hole 20 does not have to be circular in plan view. In this case, the diameter D is determined by the diameter of an imaginary circle having the same area as the opening (see FIGS. 12A and 12B).

The types of the unit lattice 91 composed of a plurality of regularly arranged through holes 20 are, for example, a square lattice (FIG. 15A), a hexagonal lattice (FIG. 15B), a rectangular lattice (FIG. 15C), and a face-centered rectangular lattice. lattice (FIG. 15D). However, the type of unit cell 91 is not limited to these examples.

An example of a method for manufacturing the infrared sensor 1A of Embodiment 1 will be described below. In the method described below, an infrared sensor 1A shown in FIG. 1A is manufactured. 16A to 16E used in the following description, a cross section corresponding to the cross section 1B-1B in the infrared sensor 1A of FIG. 1A is shown. The method for manufacturing the infrared sensor 1A is not limited to the following example.

First, a Si substrate 401 is prepared. Next, the upper surface of the Si substrate 401 is thermally oxidized to form an insulating film 402 made of SiO ₂ . In this way, the base substrate 11 is obtained. Next, a beam layer 403 is formed on the upper surface of the insulating film 402 (FIG. 16A). The beam layer 403 can be formed by a known thin film forming method such as a chemical vapor deposition method (CVD method), for example. As the material constituting the beam layer 403, a material that can form the beam 13, the first region 301, and the second region 302 is selected. The material constituting the beam layer 403 is, for example, a material that changes into the first region 301 and the second region 302 by doping. As the material constituting the beam layer 403, a material that can also form the infrared light receiving section 12A may be selected. The thickness of the beam layer 403 is, for example, 10 nm or more and 500 nm or less.

Next, as shown in FIG. 16B, a plurality of through holes 20 are formed in the beam layer 403, which are regularly arranged in plan view. For example, electron beam lithography can be used to form the through holes 20 having a period P of approximately 100 nm or more and 300 nm or less. Block copolymer lithography can be used to form the through holes 20 having a period P of approximately 1 nm or more and 100 nm or less. Further, block copolymer lithography is suitable for forming a phononic crystal structure A including a plurality of domains having mutually different shapes in plan view, for example, the phononic crystal structure A shown in FIG. 11.

Next, as shown in FIG. 16C, the shape of the beam 13 is constructed and the recess 17 is formed by photolithography and selective etching on the beam layer 403 and the insulating film 402. By forming the recess 17, the portion of the beam layer 403 that has changed into the above shape is separated from the base substrate 11.

Next, as shown in FIG. 16D, the portions of the beam layer 403 that have changed in shape are doped to form the first region 301, the second region 302, and the bonding region 303. The portion that changes to the first region 301 is doped, for example, to the p-type, and the portion that changes to the second region 302 is doped, for example, to the n-type. For the subsequent formation of wirings 15A and 15B, doping may be performed even to the portion overlapping with base substrate 11 in plan view.

Next, as shown in FIG. 16E, an infrared light receiving section 12A is formed on the upper surface of the beam 13 so as to be in contact with the bonding region 303. In addition, a first wiring 15A and a second wiring 15B electrically connected to each of the first region 301 and the second region 302 are formed. The wirings 15A and 15B can be formed by, for example, photolithography and sputtering. Subsequently, signal processing circuits 14A and 14B are formed on base substrate 11. Furthermore, necessary electrical connections are secured, and the infrared sensor 1A of the first embodiment is obtained. The infrared light receiving section 12A and the signal processing circuits 14A and 14B can be formed by a known method.

In principle, the infrared sensor 1A in FIG. 1A functions alone as an infrared sensor. A plurality of infrared sensors 1A may be arranged on the base substrate 11, with each infrared sensor 1A serving as one pixel. The array structure in which a plurality of infrared sensors 1A are arranged makes it possible, for example, to image an object having a finite temperature and/or to evaluate the intensity distribution of infrared radiation or laser beams.

(Embodiment 2)
An infrared sensor of Embodiment 2 is shown in FIGS. 17A and 17B. FIG. 17B shows a cross section 17B-17B of the infrared sensor 1B of FIG. 17A. Infrared sensor 1B in FIGS. 17A and 17B is a thermopile infrared sensor.

The beam 13 of the infrared sensor 1B includes a base layer 321 and a thermocouple layer 322 disposed on the base layer 321. The beam 13 has a laminated structure of a base layer 321 and a thermocouple layer 322. The thermocouple layer 322 includes a first region 301 having a first Seebeck coefficient, a second region 302 having a second Seebeck coefficient different from the first Seebeck coefficient, and a first region 301 and a second region 302 having a second Seebeck coefficient different from the first Seebeck coefficient. It has a bonding area 303 where the areas 302 and 302 are bonded to each other. The first region 301 and the second region 302 are joined to each other at one end 304, 305 of each. The first region 301 and the second region 302 joined in the joining region 303 constitute a thermocouple element. The joining region 303 is located at a position overlapping with the infrared sensor 1B in plan view. The bonding region 303 is located, for example, at the center of the infrared sensor 1B in plan view. The infrared light receiving section 12A and the joining region 303 in the beam 13 are joined to each other. In this embodiment, for example, amorphous Si can be used as the base layer 321. Amorphous Si has low thermal conductivity as a material. Therefore, in this aspect, for example, further improvement in infrared light receiving sensitivity comes into view.

The other configurations of the infrared sensor 1B of the second embodiment are the same as the corresponding configurations of the infrared sensor 1A of the first embodiment, including preferred aspects. Further, the operating principle of the infrared sensor 1B of the second embodiment is the same as that of the infrared sensor 1A of the first embodiment.

The infrared sensor 1B of the second embodiment can be manufactured by applying the manufacturing method of the infrared sensor 1A of the first embodiment.

(Embodiment 3)
An infrared sensor of Embodiment 3 is shown in FIGS. 18A and 18B. FIG. 18B shows a cross section 18B-18B of the infrared sensor of FIG. 18A. Infrared sensor 1C in FIGS. 18A and 18B is a thermopile infrared sensor.

The infrared sensor 1C further includes a first support 31A and a second support 31B arranged on the upper surface 16 of the base substrate 11. The first support column 31A and the second support column 31B extend in a direction away from the upper surface 16 of the base substrate 11. The beam 13 has a connecting portion 131A connected to the first support 31A and a connecting portion 131B connected to the second support 31B. Furthermore, the beam 13 has a spaced apart portion 132 spaced apart from the base substrate 11 . The beam 13 has connecting portions 131A and 131B at both ends. The infrared light receiving section 12A and the beam 13 are joined to each other at the separation section 132. The infrared light receiving section 12A is joined to the upper surface of the beam 13. The position where the infrared light receiving section 12A and the beam 13 are joined is between both ends of the beam 13, more specifically, near the center of the beam 13. The infrared light receiving section 12A is supported by a beam 13 having a spacing section 132 while being spaced apart from the base substrate 11. In a cross-sectional view, the infrared light receiving section 12A and the beam 13 are suspended above the base substrate 11 by the support columns 31A and 31B. The beam 13 is a double-end beam. In this aspect, in plan view, the ratio of the area of the infrared light receiving section 12A to the area of the infrared sensor 1C can be increased. This ratio is known to those skilled in the art as the fill factor.

The first region 301 and the first wiring 15A are electrically connected via the first pillar 31A. The second region 302 and the second wiring 15B are electrically connected via the second pillar 31B.

The first support column 31A and the second support column 31B are made of a conductive material. The conductive material is, for example, metal. The metals forming the first support pillar 31A and the second support pillar 31B are, for example, Cu and Al. However, the materials constituting the first support column 31A and the second support column 31B are not limited to the above example.

The infrared sensor 1C may further include an infrared reflective film on the upper surface 16 of the base substrate 11. In this form, the light receiving sensitivity of the infrared sensor 1C can be further increased. The materials constituting the infrared reflective film are, for example, Al and Au. However, the material constituting the infrared reflective film is not limited to the above example.

The other configurations of the infrared sensor 1C of the third embodiment, including preferred aspects, are the same as the corresponding configuration of the infrared sensor 1A of the first embodiment. Further, the operating principle of the infrared sensor 1C of the third embodiment is the same as that of the infrared sensor 1A of the first embodiment.

An example of a method for manufacturing the infrared sensor 1C of Embodiment 3 will be described below. In the method described below, the infrared sensor 1C shown in FIG. 18A is manufactured. 19A to 19D used in the following description, a cross section corresponding to the cross section 18B-18B in the infrared sensor 1C of FIG. 18A is shown. The method for manufacturing the infrared sensor 1C is not limited to the following example.

First, the base substrate 11 is prepared. Next, the signal processing circuit 14, wiring 15A, and wiring 15B are formed on the upper surface 16 of the base substrate 11 (FIG. 19A). For forming the signal processing circuit 14, the wiring 15A, and the wiring 15B, known methods including a thin film forming method such as a sputtering method or a vapor deposition method, and a pattern forming method such as a photolithography method can be used. An infrared reflective film may be formed on the upper surface 16 of the base substrate 11 together with the signal processing circuit 14, the wiring 15A, and the wiring 15B.

Next, as shown in FIG. 19B, a sacrificial layer 404 and a beam layer 403 are sequentially formed on the upper surface 16 of the base substrate 11. The sacrificial layer 404 can be formed to cover the signal processing circuit 14, the wiring 15A, and the wiring 15B. The sacrificial layer 404 is typically made of resin. As the thickness of the sacrificial layer 404, the distance between the beam 13 and the base substrate 11 in the infrared sensor 1C to be manufactured can be selected. The resin is, for example, polyimide. The sacrificial layer 404 can be formed by a known thin film forming method such as a CVD method, a sputtering method, or a spin coating method. The material constituting the beam layer 403 is as described above. The thickness of the beam layer 403 is, for example, 10 nm or more and 500 nm or less. Subsequently, a plurality of through holes 20 are formed in the beam layer 403, which are regularly arranged in a plan view. However, illustration of the through hole 20 in FIG. 19B and FIGS. 19C and 19D described later is omitted. The method for forming the through hole 20 is as described above.

Next, as shown in FIG. 19C, a first region 301, a second region 302, a bonding region 303, a first support 31A, a second support 31B, and an infrared light receiving section 12A are formed. The above-described photolithography, selective etching, and doping can be used to form the first region 301, the second region 302, and the junction region 303. The formation of the first pillar 31A and the second pillar 31B includes selective etching to secure a space for forming the pillars 31A and 31B, and a sputtering method to form the pillars 31A and 31B in the secured space. Alternatively, a thin film forming method such as a vapor deposition method can be used. The infrared light receiving section 12A can be formed by a known method.

Next, as shown in FIG. 19D, the sacrificial layer 404 is removed by selective etching to obtain the infrared sensor 1C of the third embodiment.

(Embodiment 4)
An infrared sensor according to Embodiment 4 is shown in FIG. The infrared sensor 1D in FIG. 20 is a thermopile infrared sensor.

The beam 13 has a connecting portion 131 connected to the base substrate 11 and a spacing portion 132 spaced apart from the base substrate 11. The beam 13 has a connecting portion 131 at one end. The infrared light receiving section 12A and the beam 13 are joined to each other at the separation section 132. More specifically, the infrared light receiving section 12A and the beam 13 are connected to each other at the other end of the beam 13 located in the separation section 132. The infrared light receiving section 12A is supported by a beam 13 having a spacing section 132 while being spaced apart from the base substrate 11. Beam 13 is a cantilever beam.

The base substrate 11 has a recess 17 on the upper surface 16 where the infrared light receiving section 12A is provided. The recess 17 is located between the infrared light receiving section 12A and the beam 13, and the base substrate 11. In a cross-sectional view, the infrared light receiving section 12A and the beam 13 are suspended above the recess 17 of the base substrate 11.

Beam 13 includes a base layer 321 and a thermocouple layer 322 disposed on base layer 321. The thermocouple layer 322 includes a first region 301 having a first Seebeck coefficient, a second region 302 having a second Seebeck coefficient different from the first Seebeck coefficient, and a first region 301 and a second region 302 having a second Seebeck coefficient different from the first Seebeck coefficient. It has a bonding area 303 where the areas 302 and 302 are bonded to each other. The first region 301 and the second region 302 are joined to each other at one end 304, 305 of each. The first region 301 and the second region 302 joined in the joining region 303 constitute a thermocouple element. The infrared light receiving section 12A and the joining region 303 in the beam 13 are joined to each other.

The first wiring 15A is electrically connected to the first region 301 at the other end 306 of the first region 301. The end portion 306 is located at the connection portion 131 of the beam 13. The second wiring 15B is electrically connected to the second region 302 at the other end 307 of the second region 302. The end portion 307 is located at the connection portion 131 of the beam 13. The first wiring 15A electrically connects the first region 301 in the beam 13 and the first signal processing circuit 14A. The second wiring 15B electrically connects the second region 302 in the beam 13 and the second signal processing circuit 14B.

A section 134 of the beam 13 located between a joint 133 with the infrared light receiving section 12A and a joint 131 with the base substrate 11, the first wiring 15A, and the second wiring 15B has a phononic crystal structure A. have.

The other configurations of the infrared sensor 1D of the fourth embodiment are the same as the corresponding configurations of the infrared sensor 1A of the first embodiment, including preferred aspects. Further, the operating principle of the infrared sensor 1D of the fourth embodiment is the same as that of the infrared sensor 1A of the first embodiment.

The infrared sensor 1D of the fourth embodiment can be manufactured by applying the manufacturing method of the infrared sensor 1A of the first embodiment.

(Embodiment 5)
An infrared sensor of Embodiment 5 is shown in FIGS. 21A and 21B. FIG. 21B shows a cross section 21B-21B of the infrared sensor 1E of FIG. 21A. The infrared sensor 1E in FIGS. 21A and 21B is a bolometer infrared sensor. The infrared sensor 1E includes a base substrate 11, a bolometer infrared receiver 12B, and a beam 13. Further, the infrared sensor 1E includes a first signal processing circuit 14A, a second signal processing circuit 14B, a first wiring 15A, and a second wiring 15B. The signal processing circuits 14A and 14B are provided on the base substrate 11. Wiring lines 15A and 15B are provided on base substrate 11 and beam 13.

The beam 13 has a connecting portion 131 connected to the base substrate 11 and a spacing portion 132 spaced apart from the base substrate 11. The beam 13 has connecting portions 131 at both ends. The infrared light receiving section 12B and the beam 13 are joined to each other at the separation section 132. The infrared light receiving section 12B is joined to the upper surface of the beam 13. The position where the infrared light receiving section 12B and the beam 13 are joined is between both ends of the beam 13, more specifically, near the center of the beam 13. The infrared light receiving section 12B is supported by a beam 13 having a spacing section 132 while being spaced apart from the base substrate 11. The beam 13 is a double-end beam.

The base substrate 11 has a recess 17 on the upper surface 16 where the infrared light receiving section 12B is provided. In plan view, the area of the recess 17 is larger than the area of the infrared light receiving section 12B. Further, in a plan view, the infrared light receiving section 12B is surrounded by the outer edge of the recess 17. The recess 17 is located between the infrared light receiving section 12B and the beam 13, and the base substrate 11. In a cross-sectional view, the infrared light receiving section 12B and the beam 13 are suspended above the recess 17 of the base substrate 11. Note that both ends of the beam 13 are connected to the side walls of the recess 17.

The first wiring 15A and the second wiring 15B are electrically connected to the infrared light receiving section 12B. The first wiring 15A is electrically connected to the first signal processing circuit 14A. The second wiring 15B is electrically connected to the second signal processing circuit 14B.

A section 134 (134A, 134B) in the beam 13 located between the joint 133 with the infrared light receiving part 12B and the connection part 131 with the base substrate 11 has a phononic crystal structure A. When the beam 13 has a plurality of sections 134, all the sections have the phononic crystal structure A, for example.

When infrared rays are incident on the infrared light receiving section 12B, the temperature of the infrared light receiving section 12B increases. At this time, the temperature of the infrared light receiving section 12B increases more as it is thermally insulated from the base substrate 11, which is a heat bath, and the members on the base substrate 11. In the bolometer infrared light receiving section 12B, a change in electrical resistance occurs as the temperature rises. The resulting change in electrical resistance is processed by signal processing circuits 14A and 14B, and infrared rays are detected. Depending on the signal processing, the infrared sensor 1E can measure the intensity of infrared rays and/or measure the temperature of the object.

In the infrared sensor 1E of FIGS. 21A and 21B, the first wiring 15A and the second wiring 15B have a section spaced apart from the base substrate 11. This section of the first wiring 15A is located between the connection part with the infrared light receiving section 12B and the first signal processing circuit 14A. This section of the second wiring 15B is located between the connection part with the infrared light receiving section 12B and the second signal processing circuit 14B. Each of the sections of the first wiring 15A and the second wiring 15B is in contact with the surface of the beam 13. Each of the sections of the first wiring 15A and the second wiring 15B may be a part of the beam 13. For example, this section can be formed by forming a part of the beam 13 with a doped semiconductor.

In the fifth embodiment, the first wiring 15A and/or the second wiring 15B may have the phononic crystal structure A. In this form, conduction of heat via the first wiring 15A and/or the second wiring 15B is suppressed. Therefore, the light receiving sensitivity of the infrared sensor 1E can be further improved.

When the first wiring 15A and/or the second wiring 15B have a phononic crystal structure A, each of the phononic crystal structures A of the beam 13 and the first wiring 15A is composed of a plurality of common through holes. You can leave it there. Further, each of the phononic crystal structures A of the beam 13 and the second wiring 15B may be composed of a plurality of common through holes. In this form, the light receiving sensitivity of the infrared sensor 1E can be further improved. Further, since the phononic crystal structure A can be formed simultaneously on the beam 13, the first wiring 15A, and the second wiring 15B, this form is excellent in manufacturability.

The infrared light receiving section 12B typically has a laminated structure of a variable resistance layer 121 and an infrared absorbing layer 122 provided on the variable resistance layer 121. The infrared absorbing layer 122 is usually located at the outermost layer of the infrared receiving section 12B.

The variable resistance layer 121 is made of a material whose electrical resistance changes significantly depending on temperature. The materials forming the variable resistance layer 121 are, for example, Pt, amorphous Si, and vanadium oxide. These materials have large temperature coefficients of resistance. However, the material constituting the variable resistance layer 121 is not limited to the above example.

The infrared absorbing layer 122 is made of, for example, a metal such as Ti, Cr, Au, Al, or Cu, an oxide such as SiO ₂ , and a nitride such as TiN or SiN. However, the material constituting the infrared absorbing layer 122 is not limited to the above example. When the infrared absorption layer 122 has conductivity, the infrared light receiving section 12B usually has an insulating layer between the variable resistance layer 121 and the infrared absorption layer 122.

The other configurations of the infrared sensor 1E of the fifth embodiment are the same as the corresponding configurations of the infrared sensor 1A of the first embodiment, including preferred aspects.

The infrared sensor 1E of the fifth embodiment can be manufactured by a known method including a thin film forming method such as a sputtering method or a vapor deposition method, and a microfabrication method such as a photolithography method or a selective etching method. Moreover, the infrared sensor 1E can be manufactured by applying the manufacturing method of the infrared sensor 1A of the first embodiment described above.

(Embodiment 6)
An infrared sensor of Embodiment 6 is shown in FIGS. 22A and 22B. FIG. 22B shows a cross section 22B-22B of the infrared sensor 1F of FIG. 22A. The infrared sensor 1F in FIGS. 22A and 22B is a bolometer infrared sensor.

The beam 13 has a connecting portion 131 connected to the base substrate 11 and a spacing portion 132 spaced apart from the base substrate 11. The beam 13 has a connecting portion 131 at one end. The infrared light receiving section 12B and the beam 13 are joined to each other at the separation section 132. More specifically, the infrared light receiving section 12B and the beam 13 are connected to each other at the other end of the beam 13 located in the separation section 132. The infrared light receiving section 12B is supported by a beam 13 having a spacing section 132 while being spaced apart from the base substrate 11. Beam 13 is a cantilever beam.

The base substrate 11 has a recess 17 on the upper surface 16 where the infrared light receiving section 12B is provided. The recess 17 is located between the infrared light receiving section 12B and the beam 13, and the base substrate 11. In a cross-sectional view, the infrared light receiving section 12B and the beam 13 are suspended above the recess 17 of the base substrate 11.

The first wiring 15A and the second wiring 15B are electrically connected to the infrared light receiving section 12B. The first wiring 15A is electrically connected to the first signal processing circuit 14A. The second wiring 15B is electrically connected to the second signal processing circuit 14B.

A section 134 of the beam 13 located between the joint 133 with the infrared light receiving section 12B and the joint 131 with the base substrate 11 has a phononic crystal structure A.

The other configurations of the infrared sensor 1F of the sixth embodiment are the same as the corresponding configurations of the infrared sensor 1E of the fifth embodiment, including preferred aspects. Further, the operating principle of the infrared sensor 1F of the sixth embodiment is the same as that of the infrared sensor 1E of the fifth embodiment.

The infrared sensor 1F of the sixth embodiment can be manufactured by a known method including a thin film forming method such as a sputtering method or a vapor deposition method, and a microfabrication method such as a photolithography method or a selective etching method. Moreover, the infrared sensor 1F can also be manufactured by applying the manufacturing method of the infrared sensor 1A of the first embodiment described above.

(Embodiment 7)
An infrared sensor of Embodiment 7 is shown in FIGS. 23A and 23B. FIG. 23B shows a cross section 23B-23B of the infrared sensor 1G of FIG. 23A. The infrared sensor 1G in FIGS. 23A and 23B is a bolometer infrared sensor.

The infrared sensor 1G further includes a first support 31A and a second support 31B arranged on the upper surface 16 of the base substrate 11. The first support column 31A and the second support column 31B extend in a direction away from the upper surface 16 of the base substrate 11. The beam 13 has a connecting portion 131A connected to the first support 31A and a connecting portion 131B connected to the second support 31B. Furthermore, the beam 13 has a spaced apart portion 132 spaced apart from the base substrate 11 . The beam 13 has connecting portions 131A and 131B at both ends. The infrared light receiving section 12B and the beam 13 are joined to each other at the separation section 132. The infrared light receiving section 12B is joined to the upper surface of the beam 13. The position where the infrared light receiving section 12B and the beam 13 are joined is between both ends of the beam 13, more specifically, near the center of the beam 13. The infrared light receiving section 12B is supported by a beam 13 having a spacing section 132 while being spaced apart from the base substrate 11. In a cross-sectional view, the infrared light receiving section 12B and the beam 13 are suspended above the base substrate 11 by the support columns 31A and 31B. The beam 13 is a double-end beam.

The first wiring 15A and the second wiring 15B are electrically connected to the infrared light receiving section 12B. The first wiring 15A is electrically connected to the first signal processing circuit 14A while including the first pillar 31A as a part thereof. The second wiring 15B is electrically connected to the second signal processing circuit 14B while including the second pillar 31B in a part thereof.

Sections 134A and 134B of the beam 13 located between the joint 133 with the infrared light receiving part 12B and the connection part 131 with the base substrate 11 each have a phononic crystal structure A. When the beam 13 has a plurality of sections 134 located between the joint portion 133 and the connection portion 131, all the sections may have the phononic crystal structure A.

The other configurations of the infrared sensor 1G of the seventh embodiment are the same as the corresponding configurations of the infrared sensor 1E of the fifth embodiment, including preferred aspects. Further, the specific configurations of the first support column 31A and the second support column 31B are as described above in the description of the third embodiment. The operating principle of the infrared sensor 1G of the seventh embodiment is the same as that of the infrared sensor 1E of the fifth embodiment.

The infrared sensor 1G of Embodiment 7 can be manufactured by a known method including a thin film forming method such as a sputtering method or a vapor deposition method, and a microfabrication method such as a photolithography method or a selective etching method. Moreover, the infrared sensor 1G can also be manufactured by applying the manufacturing method of the infrared sensor 1C of the third embodiment described above.

[Phononic crystal]
The phononic crystal of the present disclosure has a phononic crystal structure A. The phononic crystal of the present disclosure is a membrane-like body having a plurality of regularly arranged through holes. The thickness of the film-like body is typically 10 nm or more and 500 nm or less.

More specifically, the phononic crystal of the present disclosure includes a first domain and a second domain that are phononic crystal regions. The first domain is composed of a plurality of through holes regularly arranged in a first direction in a plan view of the phononic crystal. The second domain is composed of a plurality of through holes regularly arranged in a second direction different from the first direction in a plan view of the phononic crystal.

The phononic crystal of the present disclosure may have a phononic crystal structure A shown in FIGS. 2, 5, 7, 9, 10, 11, 13, or 14, for example.

The phononic crystal of the present disclosure has low thermal conductivity in the in-plane direction. That is, the phononic crystal of the present disclosure exhibits high thermal insulation properties in the in-plane direction. The phononic crystal of the present disclosure can be used, for example, in various applications that require high heat insulation in the in-plane direction.

The infrared sensors of the present disclosure can be used in a variety of applications, including those of conventional infrared sensors.

1A, 1B, 1C, 1D, 1E, 1F, 1G Infrared sensor 11 Base board 12A (Thermopile) Infrared receiving section 12B (Bolometer) Infrared receiving section 13 Beam 14 Signal processing circuit 14A First signal processing circuit 14B Second signal Processing circuit 15A first wiring 15B second wiring 16 top surface 17 recess 20 through hole 21A first domain 21B second domain 22 phononic polycrystalline structure 23A, 23B orientation 25 interface 31A first pillar 31B second pillar 91, 91A, 91B Unit cell 92 Region 93 Region 121 Variable resistance layer 122 Infrared absorbing layer 131 Connection portion 132 Separation portion 133 Joint portion 134, 134A, 134B Section 201 Region 202 Region 301 First region 302 Second region 303 Junction region 304 End 305 End 306 End 307 End 401 Base substrate 402 Insulating layer 403 Beam layer 404 Sacrificial layer

Claims (19)

An infrared sensor, comprising:
Base board;
Infrared receiver; and beam;
here,
The beam has a connection portion connected to the base substrate and/or a member on the base substrate, and a separation portion spaced apart from the base substrate,
The infrared light receiving part and the beam are joined to each other at the separation part,
The infrared light receiving section is supported by the beam having the spacing section while being spaced apart from the base substrate,
A section of the beam located between the joint part with the infrared light receiving part and the connection part has a phononic crystal structure constituted by a plurality of regularly arranged through holes,
The phononic crystal structure includes a first domain and a second domain that are phononic crystal regions,
The first domain is composed of the plurality of through holes regularly arranged in a first direction in a plan view,
The second domain is composed of the plurality of through holes regularly arranged in a second direction different from the first direction in a plan view,
an interface exists between the first domain and the second domain, and
The infrared receiver is a thermopile infrared receiver or a bolometer infrared receiver:
When the infrared receiving section is a thermopile infrared receiving section,
The beam includes a first region having a first Seebeck coefficient, a second region having a second Seebeck coefficient different from the first Seebeck coefficient, and the first region and the second region. a bonding region in which the bonding regions are bonded to each other, and
the infrared light receiving portion and the bonding region of the beam are bonded to each other;
When the infrared receiver is a bolometer infrared receiver,
The infrared sensor further includes:
a first wiring and a second wiring electrically connected to the infrared receiving section;
a first signal processing circuit electrically connected to the first wiring; and a second signal processing circuit electrically connected to the second wiring. The infrared sensor according to claim 1,
The infrared receiving section is a thermopile infrared receiving section, and
The beam is a single layer. The infrared sensor according to claim 1,
The infrared receiving section is a thermopile infrared receiving section,
The beam includes a base layer and a thermocouple layer disposed on the base layer, and
The thermocouple layer has the first region, the second region, and the junction region. The infrared sensor according to claim 1,
The infrared receiving section is a thermopile infrared receiving section, and
The infrared sensor further includes:
a first wiring electrically connected to the first region;
a second wiring electrically connected to the second region;
a first signal processing circuit electrically connected to the first wiring; and a second signal processing circuit electrically connected to the second wiring. The infrared sensor according to claim 1,
The infrared receiver is a bolometer infrared receiver,
The first wiring and the second wiring are connected to the base substrate between the connection part with the infrared light receiving section and the first signal processing circuit or the second signal processing circuit, respectively. has a section spaced apart from, and
The spaced apart sections of the first wiring and/or the second wiring have the phononic crystal structure. The infrared sensor according to claim 1,
The infrared receiver is a bolometer infrared receiver,
The first wiring and the second wiring are connected to the base substrate between the connection part with the infrared light receiving section and the first signal processing circuit or the second signal processing circuit, respectively. has a section spaced apart from, and
The spaced apart sections of the first wiring and/or the second wiring are in contact with the surface of the beam. The infrared sensor according to claim 6,
The spaced apart sections of the first wiring and/or the second wiring have the phononic crystal structure, and
Each of the phononic crystal structures possessed by the beam and the first wiring and/or the beam and the second wiring includes the plurality of through-holes that are common to each other. The infrared sensor according to any one of claims 1 to 7,
The beam has the connecting portion at both ends, and
The infrared light receiving section and the beam are joined to each other between both ends of the beam. The infrared sensor according to any one of claims 1 to 7,
The beam has the connection portion at one end, and
The infrared light receiving section and the beam are joined to each other at the other end of the beam. The infrared sensor according to any one of claims 1 to 9,
the base substrate has a recess,
The recess is located between the infrared light receiving section and the beam, and the base substrate, and
In a cross-sectional view, the infrared light receiving section and the beam are suspended above the recess of the base substrate. The infrared sensor according to any one of claims 1 to 9,
The infrared sensor further includes a post disposed on the base substrate and extending in a direction away from the top surface of the base substrate,
here,
The beam is connected to the column at the connection portion, and
In a cross-sectional view, the infrared light receiving section and the beam are suspended above the base substrate by the support columns. The infrared sensor according to any one of claims 1 to 11,
a periodicity of the arrangement of the plurality of through holes in the first domain;
The periods of arrangement of the plurality of through holes in the second domain are equal. The infrared sensor according to any one of claims 1 to 12,
a diameter of the plurality of through holes regularly arranged in the first domain;
The diameters of the plurality of through holes regularly arranged in the second domain are equal. The infrared sensor according to any one of claims 1 to 13,
a type of unit cell formed by the plurality of through holes regularly arranged in the first domain;
The types of unit cells formed by the plurality of regularly arranged through holes in the second domain are the same. The infrared sensor according to any one of claims 1 to 14,
In plan view, the shape of the first domain and the shape of the second domain are different. The infrared sensor according to any one of claims 1 to 15,
In a plan view, the interface between the first domain and the second domain that are adjacent to each other extends in a direction inclined from the width direction of the beam in the section. The infrared sensor according to any one of claims 1 to 16,
In a plan view, the interface between the first domain and the second domain that are adjacent to each other has a bent portion. The infrared sensor according to any one of claims 1 to 17,
The phononic crystal structure has the first domain and/or the second domain that are not in contact with the sides of the beam. A phononic crystal body having a phononic crystal structure,
The phononic crystal body includes a first domain and a second domain that are phononic crystal regions,
The first domain is composed of a plurality of through holes regularly arranged in a first direction in a plan view ,
The second domain is composed of a plurality of through holes regularly arranged in a second direction different from the first direction in a plan view , and
An interface exists between the first domain and the second domain .

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